Recording telephone conversations via a USB Voice Modem


I’ve looked around quite a bit and found that it’s been over 5 years since someone asked anything related to this topic on these forums so I’ll ask again and see if anything’s changed.

I’ve got a USR 5637 Voice/Fax modem that I can use on either an XP or a Windows 7 machine. I’d love to be able to use Audacity to record telephone conversations. I note that in 2.1.1 there’s an option to record from “Modem #0 Line Record” but when I try I get the error “Error while opening sound device. Please check the recording device settings and the project sample rate.” I am aware of the sample rates and bit depths this modem supports (11025 Hz, 16 bit, mono, for example) and can adjust settings to reflect this. Still no joy. I know for a fact that this modem handily records conversations using commercial software packages, but these days there aren’t many options in this line. The “Advanced Phone Recorder” (APR) software package demo and my modem seem to work together reasonably well in XP — I get good recording results — so I’d love to pay the gentleman his registration fee, but the problem is that it’s unclear if he is going to support beyond Vista. It’s my understanding that APR works in 8 in compatibility mode, but that 10’s a total, no-guarantee crap shoot. Considering that I’m going to a 10 machine in the not-too-distant future, purchasing APR may not be my best choice.

Anyway, in principle Audacity should be able to record from this modem so… has anyone had any luck in this area? Any advice you could give a person who’s having the aforementioned difficulties?

Thanks in advance for your thoughts!!

Are you able to set the modem as the default recording device in the
Windows Sound Control Panel?
If you can, then are you able to record with “Sound Recorder” ?
If that works, then Windows is treating the modem as a valid audio device, and Audacity should be able to use it. If Windows does not treat it as a valid audio device, then Audacity will not be able to use it.

Is “Modem #0 Line Record” the recording source you choose in XP where the modem will record into Audacity? “Modem #0 Line Record” sounds more like a built-in sound card input, except that those are normally spoof inputs that are not actually connected to any hardware.


Steve and Gale,

Thank you both for your interest and your responses.

With XP, I can get into the Control Panel’s Sounds and Audio Devices menu and see that under the “Audio” tab I have the option to set either “SoundMax HD Audio” or “Modem #0 Line Playback” as my default sound playback device. Similarly, I can set either my “SoundMax HD Audio” or “Modem #0 Line Record” as my default recording device. Under the “Voice” tab the options are respectively identical for the default voice playback and voice recording devices. When I then go into XP’s “Sound Recorder” and attempt to record, up pops a window stating “Another application is recording audio. Stop recording with this other application and then try to record with Sound Recorder again.” I can’t, for the life of me, figure out what else would be recording from that. If I change the default recording device to SoundMax, Sound Recorder will record, albeit a flat line because I don’t have a microphone hooked up. In Device Manager, under “Sound, video, and game controllers” I have an entry for “Unimodem Half-Duplex Audio Device” which is present when the USR modem is plugged into a USB port, and absent when the modem is not plugged in. Under the driver’s “Properties” menu option, under “Properties”/“Audio Devices” is a"Modem Wave Driver". Windows shows that “Driver is enabled and functioning properly”.

What’s displayed Device Manager, and the modem plugged in/removed behavior, is substantially similar in Windows 7 save for the fact that under the driver’s “Properties” menu option, there’s no further “Properties” tab. A big difference is that under the Control Panel’s “Sound” menu, there’s no mention of a modem at all, anywhere. Sound recorder in Windows 7 is unbelievably basic, so I really couldn’t tell you more with respect to it.

If any of this helps to open any doors, please let me know. Again, thanks.

It’s extremely basic in XP too. That’s what makes it such a good diagnostic tool.

Most likely nothing is recording from the modem. It sounds to me like a not very good error message that really means that the device is “not available”, and there is probably no way to make the device available other than with special software that is purpose made for recording from a modem.

I’d suggest that you try your favourite search engine and look for “voice modem recorder”.
Ensure that you use a good anti-virus / malware checker before you install anything.

Hi Steve,

Your conclusion is reached despite the fact that there’s an audio device shown in Device Manager?


I read it that cbkschroeder could record from the modem under XP, presumably using Audacity:

If so, what is that recording device called under XP?

Have you on Windows 7 gone to the Recording tab of Windows Sound, right-clicked in empty space, then “Show Disabled Devices” and “Show Disconnected Devices”?


It is said to be a half-duplex device, so can play, or record, but not both simultaneously. Perhaps some other application is playing to it, or locking it (that could be Audacity).


I’m not very hopeful.
To clarify, are you able to record from the voice modem with anything other than your old “Advanced Phone Recorder” software?

I was reading it that the software package provided the drivers that turned the modem into a USB audio device recognized by Windows - that was the case with a USB modem I had in the past - but perhaps the modem is plug and play without the software package. Does the device have the same name in Windows if you uninstall the software package?


Hi Steve and Gale,

Sorry for the delay! For some reason my last post that was submitted very shortly after your responses was never approved or otherwise lost!

I CAN record using other similar packages, though APR is the best-implemented by far. The others work so far as to demonstrate that they can record in principle; they just have other issues that make APR more palatable in the end. All of these software are pretty old at this point, as you might imagine. Support in most cases is nil. That’s why being able to use Audacity has such appeal. While the analog modem part of the hardware is pretty antique, one could always have use for the voice side!

Regarding a specific software package, there isn’t one, or at least not one that implements anything with respect to the voice capabilities of the modem. In effect, there are only drivers which I can download from the USR site. It would strike me, as you say, Gale, that this modem really should behave just like a mini-sound card.

Thanks again.

I am still not 100% clear - does Audacity fail error opening sound device when recording from the modem on XP and 7, or only 7?

On the US Robotics site they rather confusingly say the modem is plug n’ play and then say the CD contains “installation essentials” drivers. Have you actually installed those drivers: If not I strongly recommend doing so. You can always uninstall them afterwards, but I can’t see any reason why you would not install those drivers.

Then restart Audacity and post the contents of Help > Audio Device Info… (top right of Audacity).

Audacity may be encountering the same error that Media Player does. Have you shut down all modem recording apps before trying to record in Media Player or Audacity?

There are other possibilities too. If you can hear both sides of the conversation in the computer then you should be able to record it into Audacity on Windows 7 using Windows WASAPI (loopback). See Tutorial - Recording Computer Playback on Windows - Audacity Manual.

If any of the recording packages you use can save an audio file then you can import that file into Audacity for editing.


For the sake of simplicity — and my not having to repeatedly crawl behind my desk to pull my modem for what might be naught! — I’ll deal with the XP machine for now. The laptop’s the 7 machine and the modem doesn’t “live” on it though it may be used on it later.

I DID install the drivers from the USR site. In Device Manager, the modem driver reports as being supplied by U. S. Robotics corporation, dated 11/01/28, and is version The unimodem half-duplex audio device driver provider is Microsoft, the driver is dated 99/01/26, and is driver 5.1.2535.0.

I can’t imagine what else would be accessing the modem. I have shut down all apps that I know of. I have attached the output of Audio Device Info.

Other apps do save in .wav format, among others, but I’d like to use Audacity to do the recording.
deviceinfo.txt (3.6 KB)

This will probably take a lot of effort without any guarantee of success.

Run dxdiag ( pictures at, save all information and attach it.

Then disconnect the USB modem from the computer. Restart Audacity and show us Help > Audio Device Info… again.

If you look at the modem properties (when the modem is connected) there should be a setting somewhere to unmute the modem or to make it play audio. That is what you will need if you try to record the calls live into Audacity by means of playing them through your computer. That should work on Windows 7, but you need stereo mix or wave out on XP.